820-00281 no boot with battery cable

[ThisIsWes:AASP]

Clean, no corrosion anywhere. Only works if battery cable (j6951) is disconnected. When connected it draws up to 4a and no life but fans do spin. Caps light doesnt work this way. Disconnect the cable and it works fine with or without screw.

Diode to ground pins on j6951 match another board.
Tried another case/batt with no change.
Replaced U5000, U7000, U7800 in that order. No changes.

When cable is plugged in the amp meter immediately starts at 1.6a and climbs to 4a. Without cable it starts at 0.4a goes up to 1.Xa then back down to 0.4a then starts (this is normal from what I've seen).

 

[2informaticos]

Compare CHGR_A/BMON values with the good board.
Also check SMC_DCIN/BMON_ISENSE.

 

[ThisIsWes:AASP]

CHGR_AMON - .2v
CHGR_BMON - 0v in all scenarios.
SMC_DCIN - .2v
BMON_ISENSE - 0.1v in all scenarios.

My only other board has no display (possibly a dead gpu) but the values match.

 

[ThisIsWes:AASP]

forgot to add - If I connect the batt cable, connect the charger then hold power button it will shut off. I let it charge some then disconnected the charger and powered on with battery only (batt cable connected). It powers on like this but once the charger is connected it shuts off.

Going to restore and check system info.

 

[2informaticos]

Connect charger and check the exact PPBUS_G3H voltage, w/ and w/o battery connected.

Change Q7030/40/65.

 

[ThisIsWes:AASP]

PPBUS_G3H
no batt - 12.6v
batt - 11.3v up to 11.9v

changing those now...

 

[ThisIsWes:AASP]

same after changing Change Q7030/40/65.

PPBUS_G3H is still maxing out at 12v on batt/charger.

 

[2informaticos]

Check exact ohm resistance over C7020/23.
For 0.4A and 4A power consumption, CHGR_AMON should be significantly different.
Check R7020/21/22, R7060/61/62 and their traces too.

 

[ThisIsWes:AASP]

C7020/23 are 3.4ohm and 2.9 ohm which matches another board.
CHGR_AMON starts at .1v and goes up to .840v at 4.14a.
R7020/21/22, R7060/61/62 and their traces are all good.

 

[2informaticos]

Does the board boot with battery and charger in SMC bypass mode?

 

[ThisIsWes:AASP]

It does not.
I just noticed that it doesn’t need the charger to start initially after battery disconnect. Connecting the battery and pressing the power button is all it takes. This is abnormal.
this may prevent me from being able to do smc bypass.

 

[2informaticos]

So machine works with charger, or battery alone, but doesn't boot if both are connected?

What happens if start with battery alone and connect charger later?

 

[ThisIsWes:AASP]

With charger no battery - works.

With battery no charger - fans spin but no caps light or display. Responds to power button. previously it turned on with just battery but I plugged the charger in and it shut off. Hasn’t worked off battery since.

Dead battery no charger - dead battery symbol pops up.